1. Field of the Invention
The present invention generally relates to a noise reduction method and a noise reduction apparatus and, more particularly, to a noise reduction method and a noise reduction apparatus using the luminance value and the chrominance values of an input pixel so as to identify and eliminate a noise point of a digital image by adjusting the luminance value and the chrominance values.
2. Description of the Prior Art
In digital image processing, the most generally used method to reduce noise is to directly process the pixels related to the image. For example, averaging filters and sequence statistical filters are used according to respective requirements.
Conventionally, mosquito noise and Gaussian noise are eliminated using a lowpass filter, operating corresponding to the pixel values in a masked region by the filter so as to obtain a mean value and then make the mean value replace the pixel values. However, the lowpass filter performs pixel adjustment for the entire image including some non-noise portions. Therefore, the noise reduction process using the lowpass filter may lead to undesirable distortion of the image because it cannot identify where noise occurs. Moreover, since the pixel is adjusted according to the pixel values of the neighboring pixels, the adjusted image shows unnaturalness in luminance and chrominance.
Accordingly, the present invention provides a noise reduction method not only to identify noise of a digital image, but also to reduce noise by adjusting the luminance value and the chrominance values to avoid image distortion.
Compared to the prior art, the noise reduction method of the present invention exhibits excellent performance in noise reduction while remaining the original colors in the region where there is no noise determined.